Estimated GFR (eGFR)
eGFR is the clinically useful measure of kidney filtration capacity. It is the threshold metric for diagnosing chronic kidney disease.
What it measures
Glomerular filtration rate is the volume of plasma your kidneys filter per minute. True GFR can only be measured by clearance studies; routine labs report an ESTIMATED GFR derived from your serum creatinine, age, sex, and (in older formulas) race. The CKD-EPI 2021 equation is now the standard and intentionally drops race as a variable. eGFR is what kidney disease classification is built on (KDIGO stages G1–G5), and it tracks much better than creatinine alone — a serum creatinine of 1.0 means very different things at age 25 vs age 75.
What a high value can mean
- Hyperfiltration — sometimes seen in early diabetes (before nephropathy), pregnancy.
- High muscle mass overestimating clearance — limitation of creatinine-based eGFR.
- Rarely clinically actionable in the high direction.
What a low value can mean
- eGFR 60–89 — mildly reduced; often age-related, monitored.
- eGFR 45–59 (CKD G3a) — moderately reduced; primary-care management plus annual specialist input.
- eGFR 30–44 (CKD G3b) — nephrology referral.
- eGFR <30 (CKD G4–G5) — advanced kidney disease; preparation for renal replacement planning.
- Causes: diabetes, hypertension, glomerulonephritis, obstruction, drug toxicity.
When to discuss with a doctor
A single low eGFR isn't a diagnosis — chronic kidney disease requires the reduction to persist for ≥3 months. Sustained eGFR <60 warrants primary-care work-up: urine albumin/creatinine ratio, blood pressure control, medication review (avoid NSAIDs, dose-adjust as needed). eGFR <30 needs a nephrologist. Mediora.AI plots your eGFR trajectory; treatment is highly individualised.